Bike bag/pannier

Hello everyone,

I need to buy myself a business 'bag' of sorts, to go to work with but that fits nicely on a bicycle.

Anyone know of something like this?

I need it to be spacious enough to carry some clothes, a laptop and perhaps even a squash/tennis racket (although that's not that important) and it has to look elegant enough to carry into work without looking like a bicyle bag.

Thanks for any help!